The International Court of Justice is expected to issue a ruling on an effort by Iran to recover $2 billion in assets frozen by the United States.
The February 13 ruling by The Hague-based court threatens to exacerbate relations with Washington following a decision in October when the court ordered the United states to lift sanctions on humanitarian goods for Iran.
The U.S. Supreme Court ruled in 2016 that Iran must give the money to survivors and relatives of victims of terrorist attacks blamed on Tehran.
That includes the 1983 bombing of the U.S. Marine barracks in Beirut, and the 1996 Khobar Towers bombing in Saudi Arabia.
Iran said the Supreme Court decision breached a 1955 treaty with the United States and that seizure of Iranian financial assets and those of Iranian companies was illegal.
At a hearing in October, U.S. lawyers argued that Iran had "unclean hands" and that its alleged support for terrorism should disqualify the case from being heard.
Hours after that argument, the United States announced it was pulling out of the 1955 Treaty of Amity.
Tensions between the two countries are already high around the 40th anniversary of the Iranian revolution.
International Court Of Justice To Rule On Iranian Assets Frozen By U.S.
Jennifer G Newstead (L), lawyer for the United States and representative of Iran Mohsen Mohebi talk during the opening of case between Iran and the United States at the The International Court of Justice (ICJ) in the Hague, August 27, 2018.